1. Field of the Invention
This invention relates to measures for isolating vehicle occupants from blast effects due to mines, roadside bombs, rockets improvised explosive devices (IEDs), and other explosive devices.
2. Description of the Related Art
Mines, roadside bombs, rockets, improvised explosive devices (IEDs), and other explosive devices pose a major threat to vehicle occupants. Blast loads transmitted through vehicle structures and rigid body motion of the vehicle structure due to blast impulse combine to create a high likelihood of serious injury for vehicle occupants. Tremendous resources have been expended to detect and disable IEDs and related explosive devices. This is a very difficult problem and success has been limited.
As shown in FIGS. 1 and 2 a vehicle 10 includes a body structure 12 and a seat 14 for an occupant 16. Detonation of an explosive device produces a blast wave 18. A high-frequency shock component 20 of the blast wave travels through the body structure 12 and seat 14 directly to the occupant 16. A low-frequency impulse component 22 of the blast wave is coupled to the body structure 12 that can 111f and flip the vehicle. The shock component 20 represents the initial rise in pressure P of the blast wave and last for a few microseconds. The impulse component 22 represents the integral of the pressure wave P over several milliseconds.
The current state-of-the-art to counter blast effects focuses on energy absorption. A structure 24 that supports seat 14 is configured to form a “crumple zone” similar to the front end of most automobiles. The crumple zone reduces the initial high-frequency shock that is coupled directly to the occupant. The crumple zone cannot be 100% effective against the initial shock because energy and momentum must be conserved. Considerable energy is still transmitted through the mechanical linkage of the crumple zone to the occupant. Furthermore, the crumple zone does nothing to counter the low-frequency impulse effect that may lift and flip the vehicle.